The Milky Way’s quiet, introverted monster won’t spin

There’s a beast hiding at the center of the Milky Way, and it’s barely moving. This supermassive black hole, Sagittarius A* (SgrA*), has a mass 4.15 million times that of our sun. It first revealed itself to scientists as a mysterious source of radio waves from the galaxy’s center back in 1931; but it wasn’t […]